Fine-Tuning a New Planer

Careful sharpening and adjustment will give better results, but sanding after planing may still be necessary. August 23, 2005

QuestionI purchased several General machines; a table saw 350, General Intl 12" jointer and a General Intl 15" planer. I am very happy with the table saw and jointer, but pretty unhappy with the planer. There must be thousands of these machines out there made in Taiwan and imported by General Intl, Jet, Powermatic, Shop Fox, Grizzly, etc.

Below are the results of a planed piece of cherry, with new knives I purchased from Freud. Iím not sure what else I can do with this machine as I have gone over it with a fine tooth comb. I have adjusted everything four or five times now and can probably do it in my sleep. Everything is to manufactures specifics. I get a little snipe, and I can live with that, but the cherry doesnít look that well, especially for new knives. Does anyone have any thoughts?

Forum Responses(Solid Wood Machining Forum)
From contributor F:Itís not the same looking at the photo as it would be to see it live, but from what I can see it looks like I can see white fuzz type lines or streaks running down along the length of the board. I have a pretty good planer (high RPM, slow feed), but it doesnít take very many feet of hardwood (especially maple) before those dull streaks start showing up.

An unfortunate fact about a lot of wood working cutting tools is that they donít necessarily come from the manufacturer tuned up or honed to perfection. I know a lot of carpenters who have never used a truly sharp chisel in their lives because they donít come that way from the store. The end users have to flatten and polish the back themselves and hone the bevel on stones, even right off the store shelf, and the same goes for hand planes.

Freud grinds a nice, pretty straight bevel on a set of new knives, but they donít hone the bevel or polish the back. I donít hone my planer knives - I sometimes reserve a side of the knives for finish passes.

I end up using scrapers and sanding before I do any finishing, and until the knives are so dull they start leaving a lot of little beads. I finish the boards with the best finish I can get from the good side of the knives. I think the guys that are doing a lot of millwork where their product is S4S footage have ďon machine" knife grinders and the have special clearance angles for certain woods and they also will do a honing right before the finish pass. They donít have time to sand.

It looks to me like your knives are not quite sharp enough for the glass finish you desire. Unless there are heavy mill marks that are not coming through in the photo, I think your planer is tuned correctly. The cure for heavy washboard mill marks is a slower rate of feed.

From the original questioner:I was just pretty bummed that after replacing the knife with some good quality Freud knives I would get better results. The streaks have to be from the knife, but I cannot find any nicks in them, so maybe as you say they are just not sharp enough? The only good out of all of this is I know this machine inside and out and I can change the knives to within .001 with the help of a Magna set in about 20 minutes.
From contributor F:It is good to know your machine well and change out knives fast. Iím not saying Freud knives are not good knives; they are what I buy for my planer. I was just thinking that you were running some test passes while you tuned up the planer and like I said, it doesnít take a lot of footage in some woods before the streaking starts. At that stage of dullness, youíre not going to be able to see nicks or anything like on the knife edges and the glass look starts to disappear.

If you really need a good finish try polishing the backs of your knives on .375" thick float glass and fine wet or dry type sandpaper. Hone the bevel on the same thing or a sharpening stone that has a true surface on it.

From contributor S:Are you using straight HSS knives or carbide inserts? If you are using straight HSS knives I agree with Contributor F. that you cannot go wrong with polishing the face side of the knives, as most of the places that grind knives do not take the time to properly get rid of the burr that is left after the finish grind is applied.

If you are using straight HSS knives are you running two, three, or four knives in the head? Regardless of how many knives you are using only one makes the final cut, but the closer the others are to the cutting circle of that one finishing knife the cooler it will stay thus lasting longer.

Also, what angle are your knives ground to? I have found through repeated attempts that a 12 to 15 degree angle lasts longer and you are able to go from a hardwood such as maple to softwood like poplar with ease. Looking at the picture it appears to me that the burr is still on the knives, thus leaving the undesirable lines that you have. A little honing should take care of that for you.

From contributor B:The finish isn't fantastic, but coming out of a planer itís not always fantastic. There are way too many variables like the wood itself. Did you check the moisture content? Wet wood doesn't plane as good as dry wood, say 6% moisture content. A quick pass through a wide belt would solve most of your troubles.
From contributor R:I have found that on the planers like yours, if you drop the bed rollers down, and wax the bed so your lumber will slide easier, then tighten the four big allen wrench set screws that put pressure on the two rubber hold down rollers there will be more pressure on the roller on the outfeed side. When the tail end of the board clears the hold down roller there is nothing to stop the board from raising up into the knives, taking off a little more, and causing snip, but with a little added extra down pressure on the out feed side roller it will stay put.

The bed rollers just add to the problem. As the board clears the infeed bed roller, it drops back down on the bed, only .002-.003, but it makes a difference. An 8 foot outfeed roller table running very slightly uphill will help keep the very end of the board down when it clears the hold down roller on the infeed side, helping a little more on the snip. The planners are not $3,000 machines, but have been around 20 years and sold in every color of machine paint available.

From the original questioner:Contributor S - the planer takes three knives, they are HSS and I believe they have a 35 degree grind on them. They are all within .001 of each other. I am getting good at changing and setting up these blades.

Contributor B - I did not check the moisture in the cherry, it has been sitting in my heated garage for about a year and a half. I probably need to get a moisture meter at some point. I don't have a wide belt or drum sander yet.

Contributor R - I have the bed rollers at .001 above the table, and have tried them .001 below as well, and no difference. The weird thing about all of these 15" machines is that they are probably coming out of the same manufacturer in Taiwan. They have different specifics for adjusting the infeed, outfeed and chip breaker. Some say .020 below the cutting arc and other machines are supposed to be adjusted to .040? I have tried both, and still havenít had very good results. I think the knives are bad, that is the only thing that I have not been able to adjust yet.

From contributor G:Your problem could be dust collection. Some hoods are not designed very well and require a tremendous amount of vacuum. What happens is wood chips collect behind and in front of the knives because there is not enough suction to remove them. This causes an imbalance and excessive chatter.

Chatter is caused by something being out of balance. The head will take on an egg shape and there you have it. You could also have a head that was not properly balanced at the factory. The knives must also not only be properly sharpened, but also balanced. Sounds to me you don't have enough chip collection, or else a bad planner head.

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